Some dialogs do not receive focus when opened

Thanks for finding this!

Just found out what the problem was for the media library. By default, jQuery UI dialog moves the focus to the first tabbable element in the dialog, which is good.
In core/misc/ajax.js however, we have code to move the focus to the element that triggered an AJAX request.

    // If the focus hasn't be changed by the ajax commands, try to refocus the
    // triggering element or one of its parents if that element does not exist
    // anymore.
    if (
      !focusChanged &&
      this.element &&
      !$(this.element).data('disable-refocus')
    ) {
      ...
    }

So, in order to fix this problem, elements triggering a dialog need to set the data attribute data-disable-refocus to true.

We could also change core/misc/ajax.js to skip refocus when a dialog is opened, but there is a good chance this could break implementations already working around this problem. For now I've at least added the data attribute to the patch changing the media library open button in #3035316: ‘Add media’ in MediaLibraryWidget should be a button, not a link. We should probably continue the discussion here to see if there is a generic way to fix this without breaking existing implementations.

Fixing tag

@seanB What's next here? In #3035316-20: ‘Add media’ in MediaLibraryWidget should be a button, not a link you already applied what you learned here. I guess you're just letting people know what the accessibility fix is that Media did and the Block module should do the same?

If so, why is this issue listed in #2988431: [Meta] Accessibility plan for Media Library Widget?

I think it was listed in #2988431: [Meta] Accessibility plan for Media Library Widget before I solved #3035316: ‘Add media’ in MediaLibraryWidget should be a button, not a link. This is definitely no longer a media library blocker.
Shared what I learned so other people can fix it when they run into it.

👍

Removing tag and updated meta issue: #2988431-45: [Meta] Accessibility plan for Media Library Widget.

This is definitely no longer a media library blocker.

(from #21, above)

Testing on 8.9.0-dev, it appears that this IS still an issue that manifests when the Media Library is used in conjunction with Layout Builder, suggesting that the fix in #17 is not comprehensive, at least in the context of use with Layout Builder & the settings tray.

Steps to reproduce, from a generic installation
1. Create a block type with a field that uses the Media Library widget
2. Create a content type that uses Layout Builder
3. Create a node of that type and add an inline block of the type with the Media Library widget.
4. Click the "Add media" button.
5. Press the Tab key. The focus is still on the Layout Builder settings tray, not the Media Library dialog.
6. Press the ESC key. The Media Library dialog does not close, as it would if it were focused.

Scenario where the focus *does* work
1. Create a block type with a field that uses the Media Library widget
2. Use the Block UI to create a block of this type.
4. Click the "Add media" button.
5. Press the Tab key. The focus is on the Media Library dialog.
6. Press the ESC key. The Media Library dialog does close.

Presumed problem
The settings tray actions for Layout Builder to create blocks are triggered by a link with data-dialog attributes, but no way to disable refocs, which has the same underlying problem as the Media Library itself solved with #3035316: ‘Add media’ in MediaLibraryWidget should be a button, not a link.

Changes in `ajax.js` looks good to me. I Left a comment on MR for other change for explaination.

Addressed @narendraR's feedback.

Tested manually and changes looks good to me. Marking as RTBC.

The dialog focus handling was made more solid in #3397785: Dialog focus is returned to dialog instead of first tabbable element on dialog AJAX update which reduces the chances of disruption here. In combination with this, it should be possible for modules to remove most of their custom focus handling for dialogs.

gCommitted 7bd749f and pushed to 11.x. Also cherry-picked to 10.2.x. Thanks!